An article storage facility (automated warehouse) having an article transport device (travel crane (3) for carrying in and out articles) and a work platform (ladder device for maintenance work (5)) is disclosed in JP Publication of Application No. H01-158191. (The reference numerals in brackets in the present background art section are those used in JP Publication of Application No. H01-158191.) In this automated warehouse, a rack (2A, 2B) for storing articles in three dimensions is provided on each side of the crane passage (1) along which the crane (3) travels. The crane passage (1) is installed on the floor side whereas a guide rail (4) for suspending the ladder device (5) is installed on the ceiling side of the crane passage (1). Although the guide rail (4) is installed generally along the crane passage (1), the ladder storage position (4a), which is at one end side of the guide rail (4), separates from the guide rail (4) and is bent toward a side of one of the racks (2A). In other words, the ladder device (5) is configured such that it can be retracted to the ladder storage position (4a) spaced apart from the crane passage (4a) so that the ladder device (5) suspended from the guide rail (4) would not interfere with the crane (3) when transporting an article with the crane (3). (See FIG. 1, etc., of JP Publication of Application No. H01-158191.)
However, when the storage space for the work platform (ladder device (5)) is provided to one side of one (2A) of the pair of racks (2A, 2B), a large area is required along the lateral direction of the racks as an area for installing the article storage facility having the work platform (ladder device (5)) and the racks (2A, 2B). If and when the length along the lateral direction of each rack is important, then a wide area for installation is required whereas, when the racks need to be installed within a given installation area, then the length of the racks along the lateral direction needs to be shortened. In other words, the article storing efficiency for a given installation area decreases in either case.